I totally understand Henri M. It looks like the late Grand-Duchess wore indeed the tiara-element as bracelet and the bracelet attached tot the necklace-element as necklace.
It was indeed a gift from her father, King Leopold III of Belgium, but there must be a connection with Kongo, I think the origin of the diamonds.
The bracelet of HM Queen Fabiola is more as impressive, it's quite a stunning piece isn't it. Wouldn't it be a nice bandeau worn by the Duchess of Brabant